Refractory metal alloys for use in oxidation environments

ABSTRACT

A refractory metal alloy comprising principally columbium and titanium, with lesser amounts of beryllium, chromium, silicon and yttrium provides excellent resistance to air oxidation at high temperature. The broad composition range is as follows: Columbium 32.5-46 percent; Titanium 50.5-57.5 percent; Beryllium 0-8 percent; Chromium 2.15-2.6 percent; Silicon 0-8 percent; and Yttrium 0-0.1 percent; all parts by weight.

United States Patent [191 Anderson, Jr. et al.

[451 Aug. 21, 1973 I REFRACTORY METAL ALLIOYS FOR USE IN OXIDATIONENVIRONMENTS FOREIGN PATENTS OR APPLICATIONS 782,564 9/1957 GreatBritain 75/l75.5 241,676 7/1969 U.S.S.R 75/l75.5

Primary Examiner-Charles N. Lovell "Kt?ori1ey aniEI TT AndErson:WillieKrawitz et al.

[5 7] ABSTRACT A refractory metal alloy comprising principally columbiumand titanium, with lesser amounts of beryllium, chromium, silicon andyttrium provides excellent resistance to air oxidation at hightemperature.

The broad composition range is as follows: Columbium 32.5-46 percent;Titanium 50.5-57.5 percent; Beryllium 0-8 percent; Chromium 2.l5-2.6percent; Silicon 0-8 percent; and Yttrium 0-O.l percent; all parts byweight.

2 Claims, 4 Drawing Figures OXIDATION IN AIR OF A PRIOR ART ALLOY (450t-%Nb-50ot% Zr-5ot. Ti) oi I200C 8 THE PRESENT ALLOY AT I300 E 80 T. |2ooc f.- PRESENT ALLOY (COMPOSITION 9) 2 4 e 8 IO EXPOSURE TIME (Ht) Wt-GAIN(Mg /Cm PAIENIEDIIIII2I I975 sum 1 or 2 OXIDATION IN AIR OF A PRIORART A C 8 THE PRESENT ALLOY AT I300 LLOY (4501.70 Nb-50ut450T%Nb5001./Zr5OI-% Ti I200C so I PRESENT ALLOY (COMPOSITION 9) f o 20I300 c 2 4 e 8 IO 9 EXPOSURE TIME (Hr) OXIDATION IN AIRATI300 U z 60 z#5 EXPOSURE TIME (Hr) PATENTEI] AUG 21 I973 SHEET 2 BF 2 OXIDATION INAIR AT |200C EXPOSURE TIME (Hr) OXIDATION lN AIR AT IIOO C E XPOSURETIME (Hr) REFRACTORY METAL ALLOYS FOR USE IN OXIDATION ENVIRONMENTSBACKGROUND OF THE INVENTION This invention relates to new and improvedrefractory metal alloys. More specifically, this invention relates torefractory metal alloys having columbium and titanium as the principalalloy ingredients: beryllium, chromium, silicon and yttrium are minorconstituents.

Refractory alloys have been employed as castings, forgings, etc., athigh temperatures. Typical examples of refractory alloys are found inUS. Pat. Nos. 3,086,859; 2,940,845; 2,99l,l97; 2,880,088; 2,819,960;2,754,204; and 3,368,881.

However, their use at high temperature in an oxidizing environment islimited since the amount of oxidation continues with increasing timewhich eventually results in failure of the alloy as it becomes convertedinto an oxide.

It is, therefore, an object of the present invention to provide arefractory alloy which may be employed as castings, forgings, etc., in ahigh temperature, oxidizing environment such as air.

Other objects will be disclosed from the description and graphs tofollow.

According to the invention, the broad range of the components in therefractory alloy is as follows:

Columbium 32.5-46 percent; Titanium 50.5-57.5 percent; Beryllium -8percent; Chromium 2.l5-2.6 percent; Silicon 0-8 percent; and Yttrium0-0.l percent; all parts by weight.

A narrower range of components is as follows:

Columbium 33.5-44.5 percent; Titanium 52-56 percent; Beryllium 0-7.5percent; Chromium 22-25 percent; Silicon 0-7 percent, and Yttrium 0-0.lpercent; all parts by weight.

Specific alloy compositions of this invention are:

was the measured as a function of the exposure time.

In the drawings, FIGS. 1-4 are graphs showing the relationship betweenexposure time and weight gain (due to oxidation) of the alloycompositions at various oxidation temperatures in air.

FIG: i s hows a comparison of the oxidation resistance in air of alloycomposition 9 with that of a typical prior art refractory metal alloyhaving the composition at. Nb; at. Zr; 5 at. Ti. It will be observedthat the curve of composition 9 at l,300 C is well below that of theprior art alloy at l,200 C; this represents a significant improvement inoxidation resistance.

As shown in FIG. 2, compositions 2, 4, 5, and 9 show significantimprovement (about twice the oxidation resistance) over the prior artalloy when exposed to air at l,200 C.

In FIGT S, compositions 4, 5, and 7 are significantly improved over theprior art composition at l,300 C. Composition 2 was signficantly moreoxidized at l,300 C than the prior art alloy composition.

In FIG. 4, compositions l, 3, 8, and 6 performed quite well at l,l00 Cand showed no tendency to rapid oxidation.

Hence, the alloy compositions of this invention are markedly resistantto oxidation at high temperatures and show little tendency to rapidlyaccelerate in oxidation as compared to the prior art alloy. This rendersthem well suited for use as castings, forgings, etc., in air at hightemperatures.

We claim: 1. A refractory alloy composition consisting of: Columbium32.5-46 percent; Titanium 50.5-57.5. percent; Beryllium 0-8 percent;Chromium 2.l5-2.6 percent; Silicon 0-8 percent; and Yttrium 0-0.lpercent; all parts by weight.

2. A refractory alloy composition consisting of:

Columbium Titanium Beryllium Chromium Slllcon Yttrium 44. 5 52.2 1. 0 2.2 0 0. 1 44. 4 52. 2 0 2. 2 1. 1 0. 1 43. 4 52.2 1. 0 2. 2 1. 1 0. 1 42.4 52. 2 2. 0 2. 2 1. 1 0. l 41. 4 52. 2 1. 0 2. 2 3. I 0. 1 40. 9 52. 23. 5 2. 2 l. 1 0. 1 39. 4 52. 2 1. 0 2. 2 5. 1 0. 1 38. 0 52. 2 7. 5 2.2 0 0. 1 37. 4 52. 2 l. 0 2. 2 7.1 0.1 36. 9 52.2 7. 5 2. 2 l. 1 0. 133. 8 55. 9 I. 0 2. 5 6. 8 0

Columbium 33.5-44.5 percent; Titanium 52-56 percent; Beryllium 0-7.5percent; Chromium 2.2-2.5 percent; Silicon 0-7 percent; and Yttrium0-0.1

percent; all parts by weight.

* i I t

2. A refractory alloy composition consisting of: Columbium 33.5-44.5percent; Titanium 52-56 percent; Beryllium 0-7.5 percent; Chromium2.2-2.5 percent; Silicon 0-7 percent; and Yttrium 0-0.1 percent; allparts by weight.